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Albrecht MA, Price G, Lee J, Iyyalol R, Martin-Iverson MT. Dexamphetamine selectively increases 40 Hz auditory steady state response power to target and nontarget stimuli in healthy humans. J Psychiatry Neurosci 2013; 38:24-32. [PMID: 22894820 PMCID: PMC3529215 DOI: 10.1503/jpn.110145] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND An emerging endophenotype of schizophrenia is the reduction of both power and phase locking of the 40 Hz auditory steady state response (ASSR), and there have been a number of reports linking increased γ activity with positive psychotic symptoms. Schizophrenia and, more specifically, positive psychotic symptoms have been closely linked to increased dopamine (DA) neurophysiology. Therefore, we gave dexamphetamine to healthy participants to determine the effect that increased DA transmission would have on the ASSR. METHODS We administered 0.45 mg/kg of dexamphetamine orally in a double-blind placebo-controlled crossover study. Stimuli were 20 Hz and 40 Hz click trains presented in an auditory oddball-type stimulus format (probability of stimulus presentation: 0.2 for targets, 0.8 for nontargets). RESULTS We included 44 healthy volunteers (18 women) in the study. Dexamphetamine significantly increased the 40 Hz power for both target and nontarget ASSR stimuli. Dexamphetamine did not significantly affect the 40 Hz phase-locking factor (PLF) or the 20 Hz power and PLF. Whereas there were significant effects of selective attention on power and PLF for 20 and 40 Hz ASSR, there were no significant interactions between dexamphetamine and selective attention. LIMITATIONS Dexamphetamine releases both noradrenaline and DA with equal potency. Further research with selective dopaminergic and noradrenergic agents will better characterize the effects of monoamines on γ activity. CONCLUSION The results demonstrate a frequency-specific effect of dexamphetamine on the ASSR. This finding is consistent with previous research that has found an association between increased γ and positive symptoms of psychosis. However, this result also raises the possibility that previous 40 Hz ASSR findings in people with schizophrenia may be confounded by effects of antipsychotic medication. Possible neural mechanisms by which dexamphetamine specifically increases 40 Hz power are also discussed. AUSTRALIAN AND NEW ZEALAND CLINICAL TRIALS REGISTRY NUMBER: ACTRN12608000610336.
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Affiliation(s)
- Matthew A. Albrecht
- Correspondence to: M.A. Albrecht, Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Private Bag No. 1, Claremont WA, 6910, Australia;
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152
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Millan MJ. An epigenetic framework for neurodevelopmental disorders: from pathogenesis to potential therapy. Neuropharmacology 2012; 68:2-82. [PMID: 23246909 DOI: 10.1016/j.neuropharm.2012.11.015] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 11/11/2012] [Accepted: 11/22/2012] [Indexed: 12/12/2022]
Abstract
Neurodevelopmental disorders (NDDs) are characterized by aberrant and delayed early-life development of the brain, leading to deficits in language, cognition, motor behaviour and other functional domains, often accompanied by somatic symptoms. Environmental factors like perinatal infection, malnutrition and trauma can increase the risk of the heterogeneous, multifactorial and polygenic disorders, autism and schizophrenia. Conversely, discrete genetic anomalies are involved in Down, Rett and Fragile X syndromes, tuberous sclerosis and neurofibromatosis, the less familiar Phelan-McDermid, Sotos, Kleefstra, Coffin-Lowry and "ATRX" syndromes, and the disorders of imprinting, Angelman and Prader-Willi syndromes. NDDs have been termed "synaptopathies" in reference to structural and functional disturbance of synaptic plasticity, several involve abnormal Ras-Kinase signalling ("rasopathies"), and many are characterized by disrupted cerebral connectivity and an imbalance between excitatory and inhibitory transmission. However, at a different level of integration, NDDs are accompanied by aberrant "epigenetic" regulation of processes critical for normal and orderly development of the brain. Epigenetics refers to potentially-heritable (by mitosis and/or meiosis) mechanisms controlling gene expression without changes in DNA sequence. In certain NDDs, prototypical epigenetic processes of DNA methylation and covalent histone marking are impacted. Conversely, others involve anomalies in chromatin-modelling, mRNA splicing/editing, mRNA translation, ribosome biogenesis and/or the regulatory actions of small nucleolar RNAs and micro-RNAs. Since epigenetic mechanisms are modifiable, this raises the hope of novel therapy, though questions remain concerning efficacy and safety. The above issues are critically surveyed in this review, which advocates a broad-based epigenetic framework for understanding and ultimately treating a diverse assemblage of NDDs ("epigenopathies") lying at the interface of genetic, developmental and environmental processes. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Mark J Millan
- Unit for Research and Discovery in Neuroscience, IDR Servier, 125 chemin de ronde, 78290 Croissy sur Seine, Paris, France.
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153
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Lewis DA. Cortical circuit dysfunction and cognitive deficits in schizophrenia--implications for preemptive interventions. Eur J Neurosci 2012; 35:1871-8. [PMID: 22708598 DOI: 10.1111/j.1460-9568.2012.08156.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Schizophrenia is a devastating disorder that is common, usually chronic, frequently associated with substantial co-morbidity for addictive and medical disorders and, as a consequence, very costly in both personal and economic terms. At present, no proven means for preventing or modifying the course of the illness exist. This review discusses evidence supporting the ideas that: (i) impairments in certain cognitive processes are the core feature of schizophrenia; (ii) these cognitive impairments reflect abnormalities in specific cortical circuits; and (iii) these circuitry abnormalities arise during childhood-adolescence. The implications of these findings for the development and implementation of safe, preemptive, disease-modifying interventions in individuals at high risk for a clinical diagnosis of schizophrenia are considered.
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Affiliation(s)
- David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, 3811 O'Hara Street, Biomedical Science Tower W1654, Pittsburgh, PA 15213, USA.
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154
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Miranda DMD, Mamede M, Souza BRD, Almeida Barros AGD, Magno LA, Alvim-Soares A, Rosa DV, Castro CJD, Malloy-Diniz L, Gomez MV, Marco LAD, Correa H, Romano-Silva MA. Molecular medicine: a path towards a personalized medicine. BRAZILIAN JOURNAL OF PSYCHIATRY 2012; 34:82-91. [PMID: 22392394 DOI: 10.1016/s1516-4446(12)70015-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Accepted: 08/21/2011] [Indexed: 10/27/2022]
Abstract
Psychiatric disorders are among the most common human illnesses; still, the molecular and cellular mechanisms underlying their complex pathophysiology remain to be fully elucidated. Over the past 10 years, our group has been investigating the molecular abnormalities in major signaling pathways involved in psychiatric disorders. Recent evidences obtained by the Instituto Nacional de Ciência e Tecnologia de Medicina Molecular (National Institute of Science and Technology - Molecular Medicine, INCT-MM) and others using behavioral analysis of animal models provided valuable insights into the underlying molecular alterations responsible for many complex neuropsychiatric disorders, suggesting that "defects" in critical intracellular signaling pathways have an important role in regulating neurodevelopment, as well as in pathophysiology and treatment efficacy. Resources from the INCT have allowed us to start doing research in the field of molecular imaging. Molecular imaging is a research discipline that visualizes, characterizes, and quantifies the biologic processes taking place at cellular and molecular levels in humans and other living systems through the results of image within the reality of the physiological environment. In order to recognize targets, molecular imaging applies specific instruments (e.g., PET) that enable visualization and quantification in space and in real-time of signals from molecular imaging agents. The objective of molecular medicine is to individualize treatment and improve patient care. Thus, molecular imaging is an additional tool to achieve our ultimate goal.
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Affiliation(s)
- Debora Marques de Miranda
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Brazil
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155
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Shirasaka T, Hashimoto E, Ukai W, Yoshinaga T, Ishii T, Tateno M, Saito T. Stem cell therapy: social recognition recovery in a FASD model. Transl Psychiatry 2012; 2:e188. [PMID: 23149452 PMCID: PMC3565770 DOI: 10.1038/tp.2012.111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
To better understand the cellular pathogenetic mechanisms of fetal alcohol spectrum disorder (FASD) and the therapeutic benefit of stem cell treatment, we exposed pregnant rats to ethanol followed by intravenous administration of neural stem cells (NSCs) complexed with atelocollagen to the new born rats and studied recovery of GABAergic interneuron numbers and synaptic protein density in the anterior cingulate cortex, hippocampus and amygdala. Prenatal ethanol exposure reduced both parvalbumin-positive phenotype of GABAergic interneurons and postsynaptic density protein 95 levels in these areas. Intravenous NSC treatment reversed these reductions. Furthermore, treatment with NSCs reversed impaired memory/cognitive function and social interaction behavior. These experiments underscore an important role for synaptic remodeling and GABAergic interneuron genesis in the pathophysiology and treatment of FASD and highlight the therapeutic potential for intravenous NSC administration in FASD utilizing atelocollagen.
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Affiliation(s)
- T Shirasaka
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan.
| | - E Hashimoto
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - W Ukai
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - T Yoshinaga
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - T Ishii
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - M Tateno
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
| | - T Saito
- Department of Neuropsychiatry, School of Medicine, Sapporo Medical University, Chuo-ku, Sapporo, Japan
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156
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Examination of ketamine-induced deficits in sensorimotor gating and spatial learning. Physiol Behav 2012; 107:355-63. [DOI: 10.1016/j.physbeh.2012.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 08/21/2012] [Accepted: 08/29/2012] [Indexed: 11/23/2022]
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157
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Gonzalez-Burgos G, Lewis DA. NMDA receptor hypofunction, parvalbumin-positive neurons, and cortical gamma oscillations in schizophrenia. Schizophr Bull 2012; 38:950-7. [PMID: 22355184 PMCID: PMC3446219 DOI: 10.1093/schbul/sbs010] [Citation(s) in RCA: 349] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Gamma oscillations appear to be dependent on inhibitory neurotransmission from parvalbumin (PV)-containing gamma-amino butyric acid neurons. Thus, the abnormalities in PV neurons found in schizophrenia may underlie the deficits of gamma-band synchrony in the illness. Because gamma-band synchrony is thought to be crucial for cognition, cognitive deficits in schizophrenia may reflect PV neuron dysfunction in cortical neural circuits. Interestingly, it has been suggested that PV alterations in schizophrenia are the consequence of a hypofunction of signaling through N-methyl-D-aspartate (NMDA) receptors (NMDARs). Here, we review recent findings that address the question of how NMDAR hypofunction might produce deficits of PV neuron-mediated inhibition in schizophrenia. We conclude that while dysregulation of NMDARs may play an important role in the pathophysiology of schizophrenia, additional research is required to determine the particular cell type(s) that mediate dysfunctional NMDAR signaling in the illness.
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Affiliation(s)
- Guillermo Gonzalez-Burgos
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
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158
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Abstract
Biomarkers are chemical and physiologic parameters that can provide reliable and predictive information about the course and treatment of a given illness. Biomarkers are being increasingly sought after in other medical conditions, and in some instances (eg, breast cancer therapy) are beginning to be incorporated into clinical decision making. There is a confluence of research investigating potential biomarkers for schizophrenia. This article reviews early progress and strategies for evaluating biomarkers, as well as how this approach can advance the treatment of schizophrenia toward personalized medicine.
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Affiliation(s)
- Anilkumar Pillai
- Department of Psychiatry and Health Behavior, Medical College of Georgia, Georgia Health Sciences University, 997 Saint Sebastian Way, Augusta, GA 30912, USA
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159
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Selective expression of KCNS3 potassium channel α-subunit in parvalbumin-containing GABA neurons in the human prefrontal cortex. PLoS One 2012; 7:e43904. [PMID: 22937123 PMCID: PMC3427167 DOI: 10.1371/journal.pone.0043904] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 07/27/2012] [Indexed: 11/25/2022] Open
Abstract
The cognitive deficits of schizophrenia appear to be associated with altered cortical GABA neurotransmission in the subsets of inhibitory neurons that express either parvalbumin (PV) or somatostatin (SST). Identification of molecular mechanisms that operate selectively in these neurons is essential for developing targeted therapeutic strategies that do not influence other cell types. Consequently, we sought to identify, in the human cortex, gene products that are expressed selectively by PV and/or SST neurons, and that might contribute to their distinctive functional properties. Based on previously reported expression patterns in the cortex of mice and humans, we selected four genes: KCNS3, LHX6, KCNAB1, and PPP1R2, encoding K+ channel Kv9.3 modulatory α-subunit, LIM homeobox protein 6, K+ channel Kvβ1 subunit, and protein phosphatase 1 regulatory subunit 2, respectively, and examined their colocalization with PV or SST mRNAs in the human prefrontal cortex using dual-label in situ hybridization with 35S- and digoxigenin-labeled antisense riboprobes. KCNS3 mRNA was detected in almost all PV neurons, but not in SST neurons, and PV mRNA was detected in >90% of KCNS3 mRNA-expressing neurons. LHX6 mRNA was detected in almost all PV and >90% of SST neurons, while among all LHX6 mRNA-expressing neurons 50% expressed PV mRNA and >44% expressed SST mRNA. KCNAB1 and PPP1R2 mRNAs were detected in much larger populations of cortical neurons than PV or SST neurons. These findings indicate that KCNS3 is a selective marker of PV neurons, whereas LHX6 is expressed by both PV and SST neurons. KCNS3 and LHX6 might be useful for characterizing cell-type specific molecular alterations of cortical GABA neurotransmission and for the development of novel treatments targeting PV and/or SST neurons in schizophrenia.
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160
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Griesi-Oliveira K, Moreira DDP, Davis-Wright N, Sanders S, Mason C, Orabona GM, Vadasz E, Bertola DR, State MW, Passos-Bueno MR. A complex chromosomal rearrangement involving chromosomes 2, 5, and X in autism spectrum disorder. Am J Med Genet B Neuropsychiatr Genet 2012; 159B:529-36. [PMID: 22592906 DOI: 10.1002/ajmg.b.32059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Accepted: 04/18/2012] [Indexed: 12/22/2022]
Abstract
Here, we describe a female patient with autism spectrum disorder and dysmorphic features that harbors a complex genetic alteration, involving a de novo balanced translocation t(2;X)(q11;q24), a 5q11 segmental trisomy and a maternally inherited isodisomy on chromosome 5. All the possibly damaging genetic effects of such alterations are discussed. In light of recent findings on ASD genetic causes, the hypothesis that all these alterations might be acting in orchestration and contributing to the phenotype is also considered.
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Affiliation(s)
- Karina Griesi-Oliveira
- Departamento de Genética e Biologia Evolutiva, Centro de Estudos do Genoma Humano, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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161
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Section summary and perspectives: Translational medicine in psychiatry. Transl Neurosci 2012. [DOI: 10.1017/cbo9780511980053.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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162
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Catts VS, Weickert CS. Gene expression analysis implicates a death receptor pathway in schizophrenia pathology. PLoS One 2012; 7:e35511. [PMID: 22545112 PMCID: PMC3335850 DOI: 10.1371/journal.pone.0035511] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 03/16/2012] [Indexed: 12/22/2022] Open
Abstract
An increase in apoptotic events may underlie neuropathology in schizophrenia. By data-mining approaches, we identified significant expression changes in death receptor signaling pathways in the dorsolateral prefrontal cortex (DLPFC) of patients with schizophrenia, particularly implicating the Tumor Necrosis Factor Superfamily member 6 (FAS) receptor and the Tumor Necrosis Factor [ligand] Superfamily member 13 (TNFSF13) in schizophrenia. We sought to confirm and replicate in an independent tissue collection the noted mRNA changes with quantitative real-time RT-PCR. To test for regional and diagnostic specificity, tissue from orbital frontal cortex (OFC) was examined and a bipolar disorder group included. In schizophrenia, we confirmed and replicated significantly increased expression of TNFSF13 mRNA in the DLPFC. Also, a significantly larger proportion of subjects in the schizophrenia group had elevated FAS receptor expression in the DLPFC relative to unaffected controls. These changes were not observed in the bipolar disorder group. In the OFC, there were no significant differences in TNFSF13 or FAS receptor mRNA expression. Decreases in BH3 interacting domain death agonist (BID) mRNA transcript levels were found in the schizophrenia and bipolar disorder groups affecting both the DLPFC and the OFC. We tested if TNFSF13 mRNA expression correlated with neuronal mRNAs in the DLPFC, and found significant negative correlations with interneuron markers, parvalbumin and somatostatin, and a positive correlation with PPP1R9B (spinophilin), but not DLG4 (PSD-95). The expression of TNFSF13 mRNA in DLPFC correlated negatively with tissue pH, but decreasing pH in cultured cells did not cause increased TNFSF13 mRNA nor did exogenous TNFSF13 decrease pH. We concluded that increased TNFSF13 expression may be one of several cell-death cytokine abnormalities that contribute to the observed brain pathology in schizophrenia, and while increased TNFSF13 may be associated with lower brain pH, the change is not necessarily causally related to brain pH.
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Affiliation(s)
- Vibeke Sørensen Catts
- Schizophrenia Research Laboratory, Schizophrenia Research Institute, Sydney, New South Wales, Australia.
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163
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Alexander KS, Wu HQ, Schwarcz R, Bruno JP. Acute elevations of brain kynurenic acid impair cognitive flexibility: normalization by the alpha7 positive modulator galantamine. Psychopharmacology (Berl) 2012; 220:627-37. [PMID: 22038535 PMCID: PMC3666324 DOI: 10.1007/s00213-011-2539-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 10/04/2011] [Indexed: 12/28/2022]
Abstract
RATIONALE Cognitive deficits represent a core symptom cluster in schizophrenia (SZ) that is predictive of outcome but not effectively treated by current antipsychotics. Thus, there is a need for validated animal models for testing potential pro-cognitive drugs. OBJECTIVE As kynurenic acid levels are increased in prefrontal cortex (PFC) of individuals with SZ, we acutely increased brain levels of this astrocyte-derived, negative modulator of alpha7 nicotinic acetylcholine receptors (α7nAChRs) by administration of its bioprecursor kynurenine and measured the effects on extracellular kynurenic acid and glutamate levels in PFC and also performance in a set-shifting task. RESULTS Injections of kynurenine (100 mg/kg, i.p.) increased extracellular kynurenic acid (1,500%) and decreased glutamate levels (30%) in PFC. Kynurenine also produced selective deficits in set-shifting. Saline- and kynurenine-treated rats similarly acquired the compound discrimination and intra-dimensional shift (saline, 7.0 and 6.3 trials, respectively; kynurenine, 8.0 and 6.7). Both groups required more trials to acquire the initial reversal (saline, 15.3; kynurenine, 22.2). Only kynurenine-treated rats were impaired in acquiring the extra-dimensional shift (saline, 8.2; kynurenine, 21.3). These deficits were normalized by administering the α7nAChR positive allosteric modulator galantamine (3.0 mg/kg, i.p) prior to kynurenine, as trials were comparable between galantamine + kynurenine (7.8) and controls (8.2). Bilateral local perfusion of the PFC with galantamine (5.0 μM) also attenuated kynurenine-induced deficits. CONCLUSIONS These results validate the use of animals with elevated brain kynurenic acid levels in SZ research and support studies of drugs that normalize brain kynurenic acid levels and/or positively modulate α7nAChRs as pro-cognitive treatments for SZ.
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Affiliation(s)
- Kathleen S Alexander
- Department of Psychology and Neuroscience, The Ohio State University, 1835 Neil Ave., Columbus, OH 43210, USA
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164
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Nouel D, Burt M, Zhang Y, Harvey L, Boksa P. Prenatal exposure to bacterial endotoxin reduces the number of GAD67- and reelin-immunoreactive neurons in the hippocampus of rat offspring. Eur Neuropsychopharmacol 2012; 22:300-7. [PMID: 21889316 DOI: 10.1016/j.euroneuro.2011.08.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 07/18/2011] [Accepted: 08/03/2011] [Indexed: 01/03/2023]
Abstract
Epidemiological studies implicate prenatal infection as a risk factor for the development of schizophrenia and autism. Subjects with schizophrenia and autism are reported to exhibit reduced levels of glutamic acid decarboxylase 67 (GAD67), a marker for GABA neurons, in various brain regions. Reduced levels of reelin, a secretory glycoprotein present in a subpopulation of GABA neurons, have also been found in these disorders. To test if prenatal infection can cause abnormalities in GAD67 and reelin in the brains of offspring, this study used a rat model of prenatal exposure to the bacterial endotoxin, lipopolysaccharide (LPS), and assessed numbers of GAD67-immunoreactive (GAD67+) and reelin-immunoreactive (reelin+) neurons in the hippocampus of offspring. In offspring at postnatal day 14 (PD14), GAD67+ cell counts were reduced in the dentate gyrus of the prenatal LPS group compared to prenatal saline controls, while at PD28, GAD67+ cells counts were reduced in the prenatal LPS group in both the dentate gyrus and the CA1. There was a decrease in the number of reelin+ cells in the prenatal LPS offspring compared to controls in the dentate gyrus at PD14. However using Western blotting, no significant effects of prenatal LPS on levels of GAD67 or reelin protein were observed in various brain regions at PD14. These findings support the idea that prenatal infection can cause reductions in postnatal expression of GAD67 and reelin, and in this way, possibly contribute to the pathophysiology of schizophrenia or autism.
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Affiliation(s)
- Dominique Nouel
- Department of Psychiatry, McGill University, Douglas Mental Health University Institute, Montreal, Canada
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165
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Tye KM, Deisseroth K. Optogenetic investigation of neural circuits underlying brain disease in animal models. Nat Rev Neurosci 2012; 13:251-66. [PMID: 22430017 DOI: 10.1038/nrn3171] [Citation(s) in RCA: 512] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Optogenetic tools have provided a new way to establish causal relationships between brain activity and behaviour in health and disease. Although no animal model captures human disease precisely, behaviours that recapitulate disease symptoms may be elicited and modulated by optogenetic methods, including behaviours that are relevant to anxiety, fear, depression, addiction, autism and parkinsonism. The rapid proliferation of optogenetic reagents together with the swift advancement of strategies for implementation has created new opportunities for causal and precise dissection of the circuits underlying brain diseases in animal models.
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Affiliation(s)
- Kay M Tye
- Department of Bioengineering, Stanford University, 318 Campus Drive, Clark Center, Stanford, California 94305-5444, USA.
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166
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Zhang Y, Yoshida T, Katz DB, Lisman JE. NMDAR antagonist action in thalamus imposes δ oscillations on the hippocampus. J Neurophysiol 2012; 107:3181-9. [PMID: 22423006 DOI: 10.1152/jn.00072.2012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Work on schizophrenia demonstrates the involvement of the hippocampus in the disease and points specifically to hyperactivity of CA1. Many symptoms of schizophrenia can be mimicked by N-methyl-d-aspartate receptor (NMDAR) antagonist; notably, delta frequency oscillations in the awake state are enhanced in schizophrenia, an abnormality that can be mimicked by NMDAR antagonist action in the thalamus. Given that CA1 receives input from the nucleus reuniens of the thalamus, we sought to determine whether an NMDAR antagonist in the thalamus can affect hippocampal processes. We found that a systemic NMDAR antagonist (ketamine; 50 mg/kg) increased the firing rate of cells in the reuniens and CA1 in awake rats. Furthermore, ketamine increased the power of delta oscillations in both structures. The thalamic origin of the change in hippocampal properties was demonstrated in three ways: 1) oscillations in the two structures were coherent; 2) the hippocampal changes induced by systematic ketamine were reduced by thalamic injection of muscimol; and 3) the hippocampal changes could be induced by local injection of ketamine into the thalamus. Lower doses of ketamine (20 mg/kg) did not evoke delta oscillations but did increase hippocampal gamma power, an effect not dependent on the thalamus. There are thus at least two mechanisms for ketamine action on the hippocampus: a low-dose mechanism that affects gamma through a nonthalamic mechanism and a high-dose mechanism that increases CA1 activity and delta oscillations as a result of input from the thalamus. Both mechanisms may be important in producing symptoms of schizophrenia.
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Affiliation(s)
- Yuchun Zhang
- Dept. of Biology, Brandeis University, Waltham, MA, USA
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167
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de Miranda DM, Mamede M, de Souza BR, de Almeida Barros AG, Magno LA, Alvim-Soares A, Rosa DV, de Castro CJ, Malloy-Diniz L, Gomez MV, De Marco LA, Correa H, Romano-Silva MA. Molecular medicine: a path towards a personalized medicine. BRAZILIAN JOURNAL OF PSYCHIATRY 2012. [DOI: 10.1590/s1516-44462012000100015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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168
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Tejeda HA, Shippenberg TS, Henriksson R. The dynorphin/κ-opioid receptor system and its role in psychiatric disorders. Cell Mol Life Sci 2012; 69:857-96. [PMID: 22002579 PMCID: PMC11114766 DOI: 10.1007/s00018-011-0844-x] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 10/16/2022]
Abstract
The dynorphin/κ-opioid receptor system has been implicated in the pathogenesis and pathophysiology of several psychiatric disorders. In the present review, we present evidence indicating a key role for this system in modulating neurotransmission in brain circuits that subserve mood, motivation, and cognitive function. We overview the pharmacology, signaling, post-translational, post-transcriptional, transcriptional, epigenetic and cis regulation of the dynorphin/κ-opioid receptor system, and critically review functional neuroanatomical, neurochemical, and pharmacological evidence, suggesting that alterations in this system may contribute to affective disorders, drug addiction, and schizophrenia. We also overview the dynorphin/κ-opioid receptor system in the genetics of psychiatric disorders and discuss implications of the reviewed material for therapeutics development.
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Affiliation(s)
- H. A. Tejeda
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, 20 Penn St., Baltimore, MD 21201 USA
| | - T. S. Shippenberg
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
| | - R. Henriksson
- Integrative Neuroscience Section, Integrative Neuroscience Research Branch, NIDA-IRP, NIH, 333 Cassell Dr., Baltimore, MD 21224 USA
- Department of Clinical Neuroscience, Karolinska Institutet, CMM, L8:04, 17176 Stockholm, Sweden
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169
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Carmeli C, Knyazeva MG, Cuénod M, Do KQ. Glutathione precursor N-acetyl-cysteine modulates EEG synchronization in schizophrenia patients: a double-blind, randomized, placebo-controlled trial. PLoS One 2012; 7:e29341. [PMID: 22383949 PMCID: PMC3285150 DOI: 10.1371/journal.pone.0029341] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 11/25/2011] [Indexed: 12/28/2022] Open
Abstract
Glutathione (GSH) dysregulation at the gene, protein, and functional levels has been observed in schizophrenia patients. Together with disease-like anomalies in GSH deficit experimental models, it suggests that such redox dysregulation can play a critical role in altering neural connectivity and synchronization, and thus possibly causing schizophrenia symptoms. To determine whether increased GSH levels would modulate EEG synchronization, N-acetyl-cysteine (NAC), a glutathione precursor, was administered to patients in a randomized, double-blind, crossover protocol for 60 days, followed by placebo for another 60 days (or vice versa). We analyzed whole-head topography of the multivariate phase synchronization (MPS) for 128-channel resting-state EEGs that were recorded at the onset, at the point of crossover, and at the end of the protocol. In this proof of concept study, the treatment with NAC significantly increased MPS compared to placebo over the left parieto-temporal, the right temporal, and the bilateral prefrontal regions. These changes were robust both at the group and at the individual level. Although MPS increase was observed in the absence of clinical improvement at a group level, it correlated with individual change estimated by Liddle's disorganization scale. Therefore, significant changes in EEG synchronization induced by NAC administration may precede clinically detectable improvement, highlighting its possible utility as a biomarker of treatment efficacy.
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Affiliation(s)
- Cristian Carmeli
- Center for Psychiatric Neuroscience, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
- Laboratoire de Recherche en Neuroimagerie (LREN), Département des Neurosciences Cliniques (DNC), Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
| | - Maria G. Knyazeva
- Laboratoire de Recherche en Neuroimagerie (LREN), Département des Neurosciences Cliniques (DNC), Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
- Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
| | - Michel Cuénod
- Center for Psychiatric Neuroscience, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
| | - Kim Q. Do
- Center for Psychiatric Neuroscience, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Lausanne, Switzerland
- * E-mail:
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170
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Selective blockade of dopamine D3 receptors enhances while D2 receptor antagonism impairs social novelty discrimination and novel object recognition in rats: a key role for the prefrontal cortex. Neuropsychopharmacology 2012; 37:770-86. [PMID: 22030711 PMCID: PMC3261029 DOI: 10.1038/npp.2011.254] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Dopamine D(3) receptor antagonists exert pro-cognitive effects in both rodents and primates. Accordingly, this study compared the roles of dopamine D(3) vs D(2) receptors in social novelty discrimination (SND), which relies on olfactory cues, and novel object recognition (NOR), a visual-recognition task. The dopamine D(3) receptor antagonist, S33084 (0.04-0.63 mg/kg), caused a dose-related reversal of delay-dependent impairment in both SND and NOR procedures in adult rats. Furthermore, mice genetically deficient in dopamine D(3) receptors displayed enhanced discrimination in the SND task compared with wild-type controls. In contrast, acute treatment with the preferential dopamine D(2) receptor antagonist, L741,626 (0.16-5.0 mg/kg), or with the dopamine D(3) agonist, PD128,907 (0.63-40 μg/kg), caused a dose-related impairment in performance in rats in both tasks after a short inter-trial delay. Bilateral microinjection of S33084 (2.5 μg/side) into the prefrontal cortex (PFC) of rats increased SND and caused a dose-related (0.63-2.5 μg/side) improvement in NOR, while intra-striatal injection (2.5 μg/side) had no effect on either. In contrast, bilateral microinjection of L741,626 into the PFC (but not striatum) caused a dose-related (0.63-2.5 μg/side) impairment of NOR. These observations suggest that blockade of dopamine D(3) receptors enhances both SND and NOR, whereas D(3) receptor activation or antagonism of dopamine D(2) receptor impairs cognition in these paradigms. Furthermore, these actions are mediated, at least partly, by the PFC. These data have important implications for exploitation of dopaminergic mechanisms in the treatment of schizophrenia and other CNS disorders, and support the potential therapeutic utility of dopamine D(3) receptor antagonism.
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171
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Whittington MA, Roopun AK, Traub RD, Davies CH. Circuits and brain rhythms in schizophrenia: a wealth of convergent targets. Curr Opin Pharmacol 2012; 11:508-14. [PMID: 21555247 DOI: 10.1016/j.coph.2011.04.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 04/17/2011] [Indexed: 11/26/2022]
Abstract
Few common neurological illnesses trace back to single molecular disturbances. Many disparate putative causes may co-associate with a single disease state. However, uncovering functional, hierarchical networks of underlying mechanisms can provide a framework in which many primary pathologies converge on more complex, single higher level correlates of disease. This article focuses on cognitive deficits associated with schizophrenia to illustrate: a) How non-invasive EEG biomarkers of cognitive function constitute such a 'higher level correlate' of underlying pathologies. b) How derangement of multiple, cell-specific, molecular processes can converge on such EEG-visible, correlates of disrupted cognitive function. This approach suggests that evidence-based design of multi-target therapies may take advantage of hierarchical patterns of convergence to improve both efficacy and selectivity of disease-intervention.
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Affiliation(s)
- Miles A Whittington
- Institute of Neuroscience, The Medical School, Framlington Place, Newcastle University, Newcastle NE2 4HH, UK.
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172
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Singh KD. Which "neural activity" do you mean? fMRI, MEG, oscillations and neurotransmitters. Neuroimage 2012; 62:1121-30. [PMID: 22248578 DOI: 10.1016/j.neuroimage.2012.01.028] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 11/23/2011] [Accepted: 01/01/2012] [Indexed: 10/14/2022] Open
Abstract
Over the last 20 years, BOLD-FMRI has proved itself to be a powerful and versatile tool for the study of the neural substrate underpinning many of our cognitive and perceptual functions. However, exactly how it is coupled to the underlying neurophysiology, and how this coupling varies across the brain, across tasks and across individuals is still unclear. The story is further complicated by the fact that within the same cortical region, multiple evoked and induced oscillatory effects may be modulated during task execution, supporting different cognitive roles, and any or all of these may have metabolic demands that then drive the BOLD response. In this paper I shall concentrate on one experimental approach to shedding light on this problem i.e. the execution of the same experimental tasks using MEG and fMRI in order to reveal which electrophysiological responses best match the BOLD response spatially, temporally and functionally. The results demonstrate a rich and complex story that does not fit with a simplistic view of BOLD reflecting "neural activity" and suggests that we could consider the coupling between BOLD and the various parameters of neural function as an ill-posed inverse problem. Finally, I describe recent work linking individual variability in both cortical oscillations and the BOLD-fMRI response to variability in endogenous GABA concentration.
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Affiliation(s)
- Krish D Singh
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK.
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173
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Rotaru DC, Lewis DA, Gonzalez-Burgos G. The role of glutamatergic inputs onto parvalbumin-positive interneurons: relevance for schizophrenia. Rev Neurosci 2012; 23:97-109. [PMID: 22718616 DOI: 10.1515/revneuro-2011-0059] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 10/24/2011] [Indexed: 12/11/2022]
Abstract
Cognitive impairment, a core feature of schizophrenia, has been suggested to arise from a disturbance of gamma oscillations that is due to decreased neurotransmission from the parvalbumin (PV) subtype of interneurons. Indeed, PV interneurons have uniquely fast membrane and synaptic properties that are crucially important for network functions such as feedforward inhibition or gamma oscillations. The causes leading to impairment of PV neurotransmission in schizophrenia are still under investigation. Interestingly, NMDA receptors (NMDARs) antagonism results in schizophrenia-like symptoms in healthy adults. Additionally, systemic NMDAR antagonist administration increases prefrontal cortex pyramidal cell firing, apparently by producing disinhibition, and repeated exposure to NMDA antagonists leads to changes in the GABAergic markers that mimic the impairments found in schizophrenia. Based on these findings, PV neuron deficits in schizophrenia have been proposed to be secondary to (NMDAR) hypofunction at glutamatergic synapses onto these cells. However, NMDARs generate long-lasting postsynaptic currents that result in prolonged depolarization of the postsynaptic cells, a property inconsistent with the role of PV cells in network dynamics. Here, we review evidence leading to the conclusion that cortical disinhibition and GABAergic impairment produced by NMDAR antagonists are unlikely to be mediated via NMDARs at glutamatergic synapses onto mature cortical PV neurons.
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Affiliation(s)
- Diana C Rotaru
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam 1081 HV, The Netherlands
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174
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Ducharme G, Lowe GC, Goutagny R, Williams S. Early alterations in hippocampal circuitry and theta rhythm generation in a mouse model of prenatal infection: implications for schizophrenia. PLoS One 2012; 7:e29754. [PMID: 22238649 PMCID: PMC3253085 DOI: 10.1371/journal.pone.0029754] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 12/05/2011] [Indexed: 11/20/2022] Open
Abstract
Post-mortem studies suggest that GABAergic neurotransmission is impaired in schizophrenia. However, it remains unclear if these changes occur early during development and how they impact overall network activity. To investigate this, we used a mouse model of prenatal infection with the viral mimic, polyriboinosinic–polyribocytidilic acid (poly I∶C), a model based on epidemiological evidence that an immune challenge during pregnancy increases the prevalence of schizophrenia in the offspring. We found that prenatal infection reduced the density of parvalbumin- but not somatostatin-positive interneurons in the CA1 area of the hippocampus and strongly reduced the strength of inhibition early during postnatal development. Furthermore, using an intact hippocampal preparation in vitro, we found reduced theta oscillation generated in the CA1 area. Taken together, these results suggest that redistribution in excitatory and inhibitory transmission locally in the CA1 is associated with a significant alteration in network function. Furthermore, given the role of theta rhythm in memory, our results demonstrate how a risk factor for schizophrenia can affect network function early in development that could contribute to cognitive deficits observed later in the disease.
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Affiliation(s)
- Guillaume Ducharme
- Douglas Mental Health University Institute, McGill University, Department of Psychiatry, Montréal, Québec, Canada
| | - Germaine C. Lowe
- Douglas Mental Health University Institute, McGill University, Department of Psychiatry, Montréal, Québec, Canada
| | - Romain Goutagny
- Douglas Mental Health University Institute, McGill University, Department of Psychiatry, Montréal, Québec, Canada
| | - Sylvain Williams
- Douglas Mental Health University Institute, McGill University, Department of Psychiatry, Montréal, Québec, Canada
- * E-mail:
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175
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Vinogradov S, Fisher M, de Villers-Sidani E. Cognitive training for impaired neural systems in neuropsychiatric illness. Neuropsychopharmacology 2012; 37:43-76. [PMID: 22048465 PMCID: PMC3238091 DOI: 10.1038/npp.2011.251] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 09/21/2011] [Accepted: 09/21/2011] [Indexed: 01/17/2023]
Abstract
Neuropsychiatric illnesses are associated with dysfunction in distributed prefrontal neural systems that underlie perception, cognition, social interactions, emotion regulation, and motivation. The high degree of learning-dependent plasticity in these networks-combined with the availability of advanced computerized technology-suggests that we should be able to engineer very specific training programs that drive meaningful and enduring improvements in impaired neural systems relevant to neuropsychiatric illness. However, cognitive training approaches for mental and addictive disorders must take into account possible inherent limitations in the underlying brain 'learning machinery' due to pathophysiology, must grapple with the presence of complex overlearned maladaptive patterns of neural functioning, and must find a way to ally with developmental and psychosocial factors that influence response to illness and to treatment. In this review, we briefly examine the current state of knowledge from studies of cognitive remediation in psychiatry and we highlight open questions. We then present a systems neuroscience rationale for successful cognitive training for neuropsychiatric illnesses, one that emphasizes the distributed nature of neural assemblies that support cognitive and affective processing, as well as their plasticity. It is based on the notion that, during successful learning, the brain represents the relevant perceptual and cognitive/affective inputs and action outputs with disproportionately larger and more coordinated populations of neurons that are distributed (and that are interacting) across multiple levels of processing and throughout multiple brain regions. This approach allows us to address limitations found in earlier research and to introduce important principles for the design and evaluation of the next generation of cognitive training for impaired neural systems. We summarize work to date using such neuroscience-informed methods and indicate some of the exciting future directions of this field.
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Affiliation(s)
- Sophia Vinogradov
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94122, USA.
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176
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Lewis DA, Curley AA, Glausier JR, Volk DW. Cortical parvalbumin interneurons and cognitive dysfunction in schizophrenia. Trends Neurosci 2011; 35:57-67. [PMID: 22154068 DOI: 10.1016/j.tins.2011.10.004] [Citation(s) in RCA: 782] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 10/07/2011] [Accepted: 10/24/2011] [Indexed: 12/21/2022]
Abstract
Deficits in cognitive control, a core disturbance of schizophrenia, appear to emerge from impaired prefrontal gamma oscillations. Cortical gamma oscillations require strong inhibitory inputs to pyramidal neurons from the parvalbumin basket cell (PVBC) class of GABAergic neurons. Recent findings indicate that schizophrenia is associated with multiple pre- and postsynaptic abnormalities in PVBCs, each of which weakens their inhibitory control of pyramidal cells. These findings suggest a new model of cortical dysfunction in schizophrenia in which PVBC inhibition is decreased to compensate for an upstream deficit in pyramidal cell excitation. This compensation is thought to rebalance cortical excitation and inhibition, but at a level insufficient to generate the gamma oscillation power required for high levels of cognitive control.
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Affiliation(s)
- David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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177
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Wing VC, Wass CE, Soh DW, George TP. A review of neurobiological vulnerability factors and treatment implications for comorbid tobacco dependence in schizophrenia. Ann N Y Acad Sci 2011; 1248:89-106. [DOI: 10.1111/j.1749-6632.2011.06261.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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178
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Wierońska JM, Kusek M, Tokarski K, Wabno J, Froestl W, Pilc A. The GABA B receptor agonist CGP44532 and the positive modulator GS39783 reverse some behavioural changes related to positive syndromes of psychosis in mice. Br J Pharmacol 2011; 163:1034-47. [PMID: 21371011 DOI: 10.1111/j.1476-5381.2011.01301.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE An important role of GABAergic neurotransmission in schizophrenia was proposed a long time ago, but there is limited data to support this hypothesis. In the present study we decided to investigate GABA(B) receptor ligands in animal models predictive for the antipsychotic activity of drugs. The GABA(B) receptor antagonists CGP51176 and CGP36742, agonist CGP44532 and positive allosteric modulator GS39783 were studied. EXPERIMENTAL APPROACH The effects of all ligands were investigated in MK-801- and amphetamine-induced hyperactivity tests. The anti-hallucinogenic-like effect of the compounds was screened in the model of head twitches induced by (±)1-(2.5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Furthermore, the effect of GS39783 and CGP44532 on DOI-induced frequency of spontaneous excitatory postsynaptic currents (EPSCs) in slices from mouse brain frontal cortices was investigated. The anti-cataleptic properties of the compounds were also assessed. KEY RESULTS The GABA(B) receptor activators CGP44532 and GS39783 exhibited antipsychotic-like effects both in the MK-801- and amphetamine-induced hyperactivity tests, as well as in the head-twitch model in mice. Such effects were not observed for the GABA(B) receptor antagonists. DOI-induced increased frequency of spontaneous EPSCs was also decreased by the compounds. Moreover, CGP44532 and GS39783 inhibited haloperidol-induced catalepsy and EPSCs. CONCLUSION AND IMPLICATIONS These data suggest that selective GABA(B) receptor activators may be useful in the treatment of psychosis.
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Affiliation(s)
- J M Wierońska
- Department of Neurobiology, Institute of Pharmacology PAS, 31-343 Kraków, Poland
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179
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Neddens J, Fish KN, Tricoire L, Vullhorst D, Shamir A, Chung W, Lewis DA, McBain CJ, Buonanno A. Conserved interneuron-specific ErbB4 expression in frontal cortex of rodents, monkeys, and humans: implications for schizophrenia. Biol Psychiatry 2011; 70:636-45. [PMID: 21664604 PMCID: PMC5040357 DOI: 10.1016/j.biopsych.2011.04.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/15/2011] [Accepted: 04/15/2011] [Indexed: 12/16/2022]
Abstract
BACKGROUND Neuregulin-1 and ErbB4 are genetically associated with schizophrenia, and detailed knowledge of the cellular and subcellular localization of ErbB4 is important for understanding how neuregulin-1 regulates neuronal network activity and behavior. Expression of ErbB4 is restricted to interneurons in the rodent hippocampus and cortex. However, controversy remains about the cellular expression pattern in primate brain and its subcellular distribution in postsynaptic somatodendritic locations versus presynaptic terminals. METHODS ErbB4 expression was analyzed in pyramidal cells and interneurons in the frontal cortex of five species: C57BL6 mice (n = 3), ErbB4⁻/⁻ mice (n = 2), Sprague-Dawley rats (n = 3), two macaque species (n = 3 + 2), and humans (normal control subjects, n = 2). We investigated 1) messenger RNA in mice, macaques, and humans; 2) protein expression in all species using highly specific monoclonal antibodies; and 3) specificity tests of several ErbB4 antibodies on brain samples (mouse, macaque, human). RESULTS ErbB4 RNA is restricted to interneurons in the frontal cortex of mice. ErbB4 protein is undetectable in pyramidal cells of rodents, macaques, and human frontal cortex, whereas most interneurons positive for parvalbumin, calretinin, or cholecystokinin, but only a minority of calbindin-positive cells, co-express ErbB4 in macaques. Importantly, no presynaptic ErbB4 expression was detected in any species. CONCLUSIONS The interneuron-selective somatodendritic expression of ErbB4 is consistent with a primary role of neuregulin-ErbB4 signaling in the postsynaptic modulation of gamma-aminobutyric acidergic function in rodents and primates. Our data validate the use of rodents to analyze effects of abnormal ErbB4 function as a means to model endophenotypes of psychiatric disorders.
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180
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GABA neuron alterations, cortical circuit dysfunction and cognitive deficits in schizophrenia. Neural Plast 2011; 2011:723184. [PMID: 21904685 PMCID: PMC3167184 DOI: 10.1155/2011/723184] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/01/2011] [Indexed: 01/01/2023] Open
Abstract
Schizophrenia is a brain disorder associated with cognitive deficits that severely affect the patients' capacity for daily functioning. Whereas our understanding of its pathophysiology is limited, postmortem studies suggest that schizophrenia is associated with deficits of GABA-mediated synaptic transmission. A major role of GABA-mediated transmission may be producing synchronized network oscillations which are currently hypothesized to be essential for normal cognitive function. Therefore, cognitive deficits in schizophrenia may result from a GABA synapse dysfunction that disturbs neural synchrony. Here, we highlight recent studies further suggesting alterations of GABA transmission and network oscillations in schizophrenia. We also review current models for the mechanisms of GABA-mediated synchronization of neural activity, focusing on parvalbumin-positive GABA neurons, which are altered in schizophrenia and whose function has been strongly linked to the production of neural synchrony. Alterations of GABA signaling that impair gamma oscillations and, as a result, cognitive function suggest paths for novel therapeutic interventions.
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181
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Selective pyramidal cell reduction of GABA(A) receptor α1 subunit messenger RNA expression in schizophrenia. Neuropsychopharmacology 2011; 36:2103-10. [PMID: 21677653 PMCID: PMC3158308 DOI: 10.1038/npp.2011.102] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Levels of messenger RNA (mRNA) for the α1 subunit of the GABA(A) receptor, which is present in 60% of cortical GABA(A) receptors, have been reported to be lower in layer 3 of the prefrontal cortex (PFC) in subjects with schizophrenia. This subunit is expressed in both pyramidal cells and interneurons, and thus lower α1 subunit levels in each cell population would have opposite effects on net cortical excitation. We used dual-label in situ hybridization to quantify GABA(A) α1 subunit mRNA expression in calcium/calmodulin-dependent kinase II α (CaMKIIα)-containing pyramidal cells and glutamic acid decarboxylase 65 kDa (GAD65)-containing interneurons in layer 3 of the PFC from matched schizophrenia and healthy comparison subjects. In subjects with schizophrenia, mean GABA(A) α1 subunit mRNA expression was significantly 40% lower in pyramidal cells, but was not altered in interneurons. Lower α1 subunit mRNA expression in pyramidal cells was not attributable to potential confounding factors, and thus appeared to reflect the disease process of schizophrenia. These results suggest that pyramidal cell inhibition is reduced in schizophrenia, whereas inhibition of GABA neurons is maintained. The cell type specificity of these findings may reflect a compensatory response to enhance layer 3 pyramidal cell activity in the face of the diminished excitatory drive associated with the lower dendritic spine density on these neurons.
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182
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Curley AA, Arion D, Volk DW, Asafu-Adjei JK, Sampson AR, Fish KN, Lewis DA. Cortical deficits of glutamic acid decarboxylase 67 expression in schizophrenia: clinical, protein, and cell type-specific features. Am J Psychiatry 2011; 168:921-9. [PMID: 21632647 PMCID: PMC3273780 DOI: 10.1176/appi.ajp.2011.11010052] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Cognitive deficits in schizophrenia are associated with altered activity of the dorsolateral prefrontal cortex, which has been attributed to lower expression of the 67 kDa isoform of glutamic acid decarboxylase (GAD67), the major γ-aminobutyric acid (GABA)-synthesizing enzyme. However, little is known about the relationship of prefrontal GAD67 mRNA levels and illness severity, translation of the transcript into protein, and protein levels in axon terminals, the key site of GABA production and function. METHOD Quantitative polymerase chain reaction was used to measure GAD67 mRNA levels in postmortem specimens of dorsolateral prefrontal cortex from subjects with schizophrenia and matched comparison subjects with no known history of psychiatric or neurological disorders (N=42 pairs). In a subset of this cohort in which potential confounds of protein measures were controlled (N=19 pairs), Western blotting was used to quantify tissue levels of GAD67 protein in tissue. In five of these pairs, multilabel confocal immunofluorescence was used to quantify GAD67 protein levels in the axon terminals of parvalbumin-containing GABA neurons, which are known to have low levels of GAD67 mRNA in schizophrenia. RESULTS GAD67 mRNA levels were significantly lower in schizophrenia subjects (by 15%), but transcript levels were not associated with predictors or measures of illness severity or chronicity. In schizophrenia subjects, GAD67 protein levels were significantly lower in total gray matter (by 10%) and in parvalbumin axon terminals (by 49%). CONCLUSIONS The findings that lower GAD67 mRNA expression is common in schizophrenia, that it is not a consequence of having the illness, and that it leads to less translation of the protein, especially in the axon terminals of parvalbumin-containing neurons, support the hypothesis that lower GABA synthesis in parvalbumin neurons contributes to dorsolateral prefrontal cortex dysfunction and impaired cognition in schizophrenia.
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183
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Sleep correlates of cognition in early course psychotic disorders. Schizophr Res 2011; 131:231-4. [PMID: 21724373 PMCID: PMC3217835 DOI: 10.1016/j.schres.2011.05.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/24/2011] [Accepted: 05/31/2011] [Indexed: 11/24/2022]
Abstract
BACKGROUND Slow waves and sleep spindles, the main oscillations during non-rapid eye movement sleep, have been thought to be related to cognitive processes, and are impaired in psychotic disorders. Cognitive impairments, seen early in the course of psychotic disorders, may be related to alterations in these oscillations, but few studies have examined this relationship. METHOD Twenty seven untreated patients with a recently diagnosed psychotic disorder had polysomnographic sleep studies and neuro-cognitive testing. RESULTS Reduced power in the sigma range, which reflects spindle density, was associated with impaired attention, and reasoning, but not intelligence quotient (IQ). Slow wave sleep measures were not significantly associated with any cognitive measures. CONCLUSIONS Impairments in sleep spindles may be associated with cognitive deficits in the early course of psychotic disorders. These observations may help clarify neuro-biologic mechanisms of cognitive deficits in psychotic disorders such as schizophrenia.
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184
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Konradi C, Yang CK, Zimmerman EI, Lohmann KM, Gresch P, Pantazopoulos H, Berretta S, Heckers S. Hippocampal interneurons are abnormal in schizophrenia. Schizophr Res 2011; 131:165-73. [PMID: 21745723 PMCID: PMC3159834 DOI: 10.1016/j.schres.2011.06.007] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/05/2011] [Accepted: 06/09/2011] [Indexed: 02/01/2023]
Abstract
OBJECTIVE The cellular substrate of hippocampal dysfunction in schizophrenia remains unknown. We tested the hypothesis that hippocampal interneurons are abnormal in schizophrenia, but that the total number of hippocampal neurons in the pyramidal cell layer is normal. METHODS We collected whole hippocampal specimens of 13 subjects with schizophrenia and 20 matched healthy control subjects to study the number of all neurons, the somal volume of neurons, the number of somatostatin- and parvalbumin-positive interneurons and the messenger RNA levels of somatostatin, parvalbumin and glutamic acid decarboxylase 67. RESULTS The total number of hippocampal neurons in the pyramidal cell layer was normal in schizophrenia, but the number of somatostatin- and parvalbumin-positive interneurons, and the level of somatostatin, parvalbumin and glutamic acid decarboxylase mRNA expression were reduced. CONCLUSIONS The study provides strong evidence for a specific defect of hippocampal interneurons in schizophrenia and has implications for emerging models of hippocampal dysfunction in schizophrenia.
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Affiliation(s)
- Christine Konradi
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-8548, USA.
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185
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Volk DW, Radchenkova PV, Walker EM, Sengupta EJ, Lewis DA. Cortical opioid markers in schizophrenia and across postnatal development. ACTA ACUST UNITED AC 2011; 22:1215-23. [PMID: 21810780 DOI: 10.1093/cercor/bhr202] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Certain cognitive deficits in schizophrenia have been linked to dysfunction of prefrontal cortical (PFC) γ-aminobutyric acid (GABA) neurons and appear neurodevelopmental in nature. Since opioids suppress GABA neuron activity, we conducted the first study to determine 1) whether the μ opioid receptor (MOR), δ opioid receptor (DOR), and opioid ligand proenkephalin are altered in the PFC of a large cohort of schizophrenia subjects and 2) the postnatal developmental trajectory in monkey PFC of opioid markers that are altered in schizophrenia. We used quantitative polymerase chain reaction to measure mRNA levels from 42 schizophrenia and 42 matched healthy comparison subjects; 18 monkeys chronically exposed to haloperidol, olanzapine, or placebo; and 49 monkeys aged 1 week-11.5 years. We found higher levels for MOR mRNA (+27%) in schizophrenia but no differences in DOR or proenkephalin mRNAs. Elevated MOR mRNA levels in schizophrenia did not appear to be explained by substance abuse, psychotropic medications, or illness chronicity. Finally, MOR mRNA levels declined through early postnatal development, stabilized shortly before adolescence and increased across adulthood in monkey PFC. In schizophrenia, higher MOR mRNA levels may contribute to suppressed PFC GABA neuron activity and might be attributable to alterations in the postnatal developmental trajectory of MOR signaling.
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Affiliation(s)
- David W Volk
- Department of Psychiatry, University of Pittsburgh, W1655 BST, 3811 O’Hara Street, Pittsburgh, PA 15213, USA.
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186
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A novel α5GABA(A)R-positive allosteric modulator reverses hyperactivation of the dopamine system in the MAM model of schizophrenia. Neuropsychopharmacology 2011; 36:1903-11. [PMID: 21562483 PMCID: PMC3154109 DOI: 10.1038/npp.2011.76] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We have shown previously that aberrant hippocampal (HPC) output underlies the dopamine (DA) dysfunction observed in the methylazoxymethanol acetate (MAM) developmental model of schizophrenia in the rodent. This alteration of HPC activity was proposed to result from a reduction in parvalbumin (PV)-expressing GABAergic interneurons and consequent destabilization of the output of pyramidal neurons, as well as disrupted activation across a broad neural network. In vivo extracellular recordings were performed in the ventral tegmental area (VTA) and ventral HPC of saline- (SAL) and MAM-treated animals. A novel benzodiazepine-positive allosteric modulator (PAM), selective for the α5 subunit of the GABA(A) receptor, SH-053-2'F-R-CH3, was tested for its effects on the output of the HPC, leading to dopamine system hyperactivity in MAM-treated animals. In addition, the effect of SH-053-2'F-R-CH3 on the hyperactive locomotor response to amphetamine in MAM animals was examined. We demonstrate that treatment with the α5GABA(A)R PAM reduced the number of spontaneously active DA neurons in the VTA of MAM animals to levels observed in SAL rats, both when administered systemically and when directly infused into the ventral HPC. Moreover, HPC neurons in both SAL and MAM animals showed diminished cortical-evoked responses following α5GABA(A)R PAM treatment. In addition, the increased locomotor response to amphetamine observed in MAM rats was reduced following α5GABA(A)R treatment. This study supports a novel treatment of schizophrenia that targets abnormal HPC output, which in turn normalizes dopaminergic neuronal activity.
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187
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Schulman JJ, Cancro R, Lowe S, Lu F, Walton KD, Llinás RR. Imaging of thalamocortical dysrhythmia in neuropsychiatry. Front Hum Neurosci 2011; 5:69. [PMID: 21863138 PMCID: PMC3149146 DOI: 10.3389/fnhum.2011.00069] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 07/15/2011] [Indexed: 12/22/2022] Open
Abstract
Abnormal brain activity dynamics, in the sense of a thalamocortical dysrhythmia (TCD), has been proposed as the underlying mechanism for a subset of disorders that bridge the traditional delineations of neurology and neuropsychiatry. In order to test this proposal from a psychiatric perspective, a study using magnetoencephalography (MEG) was implemented in subjects with schizophrenic spectrum disorder (n = 14), obsessive–compulsive disorder (n = 10), or depressive disorder (n = 5) and in control individuals (n = 18). Detailed CNS electrophysiological analysis of these patients, using MEG, revealed the presence of abnormal theta range spectral power with typical TCD characteristics, in all cases. The use of independent component analysis and minimum-norm-based methods localized such TCD to ventromedial prefrontal and temporal cortices. The observed mode of oscillation was spectrally equivalent but spatially distinct from that of TCD observed in other related disorders, including Parkinson's disease, central tinnitus, neuropathic pain, and autism. The present results indicate that the functional basis for much of these pathologies may relate most fundamentally to the category of calcium channelopathies and serve as a model for the cellular substrate for low-frequency oscillations present in these psychiatric disorders, providing a basis for therapeutic strategies.
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Affiliation(s)
- Joshua J Schulman
- Department of Physiology and Neuroscience, New York University School of Medicine New York, NY, USA
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188
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Fast-spiking interneurons have an initial orientation bias that is lost with vision. Nat Neurosci 2011; 14:1121-3. [PMID: 21750548 PMCID: PMC3164933 DOI: 10.1038/nn.2890] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 07/05/2011] [Indexed: 12/13/2022]
Abstract
We found that in mice, following eye opening, fast-spiking, parvalbumin-positive GABAergic interneurons had well-defined orientation tuning preferences and that subsequent visual experience broadened this tuning. Broad inhibitory tuning was not required for the developmental sharpening of excitatory tuning but did precede binocular matching of excitatory orientation tuning. We propose that experience-dependent broadening of inhibition is a candidate for initiating the critical period of excitatory binocular plasticity in developing visual cortex.
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189
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McClintock SM, Freitas C, Oberman L, Lisanby SH, Pascual-Leone A. Transcranial magnetic stimulation: a neuroscientific probe of cortical function in schizophrenia. Biol Psychiatry 2011; 70:19-27. [PMID: 21571254 PMCID: PMC3270326 DOI: 10.1016/j.biopsych.2011.02.031] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/21/2011] [Accepted: 02/25/2011] [Indexed: 12/20/2022]
Abstract
Transcranial magnetic stimulation (TMS) is a neuropsychiatric tool that can serve as a useful method to better understand the neurobiology of cognitive function, behavior, and emotional processing. The purpose of this article is to examine the utility of TMS as a means to measure neocortical function in neuropsychiatric disorders in general, and schizophrenia in particular, for the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia initiative. When incorporating TMS paradigms in research studies, methodologic considerations include technical aspects of TMS, cohort selection and confounding factors, and subject safety. Available evidence suggests benefits of TMS alone or in combination with neurophysiologic and neuroimaging methods, including positron emission tomography, single photon emission computed tomography, magnetic resonance imaging, functional magnetic resonance imaging, functional near infrared spectroscopy, magnetoencephalography, and electroencephalography, to explore neocortical function. With the multiple TMS techniques including single-pulse, paired-pulse, paired associative stimulation, and repetitive TMS and theta burst stimulation, combined with neurophysiologic and neuroimaging methods, there exists a plethora of TMS experimental paradigms to modulate neocortical physiologic processes. Specifically, TMS can measure cortical excitability, intracortical inhibitory and excitatory mechanisms, and local and network cortical plasticity. Coupled with functional and electrophysiologic modalities, TMS can provide insight into the mechanisms underlying healthy neurodevelopment and aging, as well as neuropsychiatric pathology. Thus, TMS could be a useful tool in the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia armamentarium of biomarker methods. Future investigations are warranted to optimize TMS methodologies for this purpose.
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Affiliation(s)
- Shawn M. McClintock
- Brain Stimulation Lab, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA, Division of Brain Stimulation and Therapeutic Modulation, Department of Psychiatry, New York State Psychiatric Institute, Columbia University, New York, NY, USA
| | - Catarina Freitas
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Lindsay Oberman
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Sarah H. Lisanby
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham North Carolina, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA, Institut Universitari de Neurorehabilitació Guttmann, Universidad Autónoma de Barcelona, Badalona, Spain., Corresponding Author: Alvaro Pascual-Leone, MD, PhD, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA. T: 617.667-0203; Fax: 617.975-5322.
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190
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Glutamate, obsessive-compulsive disorder, schizophrenia, and the stability of cortical attractor neuronal networks. Pharmacol Biochem Behav 2011; 100:736-51. [PMID: 21704646 DOI: 10.1016/j.pbb.2011.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 05/25/2011] [Accepted: 06/09/2011] [Indexed: 12/31/2022]
Abstract
A computational neuroscience approach to the symptoms of obsessive-compulsive disorder based on a stochastic neurodynamical framework is described. An increased depth in the basins of attraction of attractor neuronal network states in the brain makes each state too stable, so that it tends to remain locked in that state, and cannot easily be moved on to another state. It is suggested that the different symptoms that may be present in obsessive--compulsive disorder could be related to changes of this type in different brain regions. In integrate-and-fire network simulations, an increase in the NMDA and/or AMPA receptor conductances, which increases the depth of the attractor basins, increases the stability of attractor networks, and makes them less easily moved on to another state by a new stimulus. Increasing GABA-receptor activated currents can partly reverse this overstability. There is now some evidence for overactivity in glutamate transmitter systems in obsessive-compulsive disorder, and the hypothesis presented here shows how some of the symptoms of obsessive-compulsive disorder could be produced by the increase in the stability of attractor networks that is produced by increased glutamatergic activity. In schizophrenia, a reduction of the firing rates of cortical neurons caused for example by reduced NMDA receptor function, present in schizophrenia, can lead to instability of the high firing rate attractor states that normally implement short-term memory and attention, contributing to the cognitive and negative symptoms of schizophrenia. Reduced cortical inhibition caused by a reduction of GABA neurotransmission, present in schizophrenia, can lead to instability of the spontaneous firing states of cortical networks, leading to a noise-induced jump to a high firing rate attractor state even in the absence of external inputs, contributing to the positive symptoms of schizophrenia.
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191
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Zic2 hypomorphic mutant mice as a schizophrenia model and ZIC2 mutations identified in schizophrenia patients. Sci Rep 2011; 1:16. [PMID: 22355535 PMCID: PMC3216504 DOI: 10.1038/srep00016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 05/23/2011] [Indexed: 12/23/2022] Open
Abstract
ZIC2 is a causal gene for holoprosencephaly and encodes a zinc-finger-type transcriptional regulator. We characterized Zic2kd/+ mice with a moderate (40%) reduction in Zic2 expression. Zic2kd/+ mice showed increased locomotor activity in novel environments, cognitive and sensorimotor gating dysfunctions, and social behavioral abnormalities. Zic2kd/+ brain involved enlargement of the lateral ventricle, thinning of the cerebral cortex and corpus callosum, and decreased number of cholinergic neurons in the basal forebrain. Because these features are reminiscent of schizophrenia, we examined ZIC2 variant-carrying allele frequencies in schizophrenia patients and in controls in the Japanese population. Among three novel missense mutations in ZIC2, R409P was only found in schizophrenia patients, and was located in a strongly conserved position of the zinc finger domain. Mouse Zic2 with the corresponding mutation showed lowered transcription-activating capacity and had impaired target DNA-binding and co-factor-binding capacities. These results warrant further study of ZIC2 in the pathogenesis of schizophrenia.
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192
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Lewis DA, Fish KN, Arion D, Gonzalez-Burgos G. Perisomatic inhibition and cortical circuit dysfunction in schizophrenia. Curr Opin Neurobiol 2011; 21:866-72. [PMID: 21680173 DOI: 10.1016/j.conb.2011.05.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 05/04/2011] [Accepted: 05/17/2011] [Indexed: 01/06/2023]
Abstract
Deficits of cognitive control in schizophrenia are associated with altered gamma oscillations in the prefrontal cortex. Paralbumin basket interneurons, which innervate the perisomatic region of pyramidal neurons, appear to play a key role in generating cortical gamma oscillations. In the prefrontal cortex of subjects with schizophrenia, alterations are present in both pre- and post-synaptic markers of the strength of GABA inputs from parvalbumin basket neurons to pyramidal neurons. These alterations may contribute to the neural substrate for impaired gamma oscillations in schizophrenia.
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Affiliation(s)
- David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States.
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193
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Papaleo F, Lipska BK, Weinberger DR. Mouse models of genetic effects on cognition: relevance to schizophrenia. Neuropharmacology 2011; 62:1204-20. [PMID: 21557953 DOI: 10.1016/j.neuropharm.2011.04.025] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 04/08/2011] [Accepted: 04/20/2011] [Indexed: 01/27/2023]
Abstract
Cognitive dysfunction is a core feature of schizophrenia. Growing evidence indicates that a wide variety of genetic mutations and polymorphisms impact cognition and may thus be implicated in various aspects of this mental disorder. Despite differences between human and rodent brain structure and function, genetic mouse models have contributed critical information about brain mechanisms involved in cognitive processes. Here, we summarize discoveries of genetic modifications in mice that impact cognition. Based on functional hypotheses, gene modifications within five model systems are described: 1) dopamine (D1, D2, D3, D4, D5, DAT, COMT, MAO); 2) glutamate (GluR-A, NR1, NR2A, NR2B, GRM2, GRM3, GLAST); 3) GABA (α(5), γ(2), α(4), δGABA(A), GABA(B(1)), GAT1); 4) acetylcholine (nAChRβ2, α7, CHRM1); and 5) calcium (CaMKII-α, neurogranin, CaMKKβ, CaMKIV). We also consider other risk-associated genes for schizophrenia such as dysbindin (DTNBP1), neuregulin (NRG1), disrupted-in-schizophrenia1 (DISC1), reelin and proline dehydrogenase (PRODH). Because of the presumed importance of environmental factors, we further consider genetic modifications within the stress-sensitive systems of corticotropin-releasing factor (CRF), brain-derived neurotrophic factor (BDNF) and the endocannabinoid systems. We highlight the missing information and limitations of cognitive assays in genetically modified mice models relevant to schizophrenia pathology.
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Affiliation(s)
- Francesco Papaleo
- Department of Neuroscience and Brain Technologies, The Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy.
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194
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Hoftman GD, Lewis DA. Postnatal developmental trajectories of neural circuits in the primate prefrontal cortex: identifying sensitive periods for vulnerability to schizophrenia. Schizophr Bull 2011; 37:493-503. [PMID: 21505116 PMCID: PMC3080694 DOI: 10.1093/schbul/sbr029] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a disorder of cognitive neurodevelopment with characteristic abnormalities in working memory attributed, at least in part, to alterations in the circuitry of the dorsolateral prefrontal cortex. Various environmental exposures from conception through adolescence increase risk for the illness, possibly by altering the developmental trajectories of prefrontal cortical circuits. Macaque monkeys provide an excellent model system for studying the maturation of prefrontal cortical circuits. Here, we review the development of glutamatergic and γ-aminobutyric acid (GABA)-ergic circuits in macaque monkey prefrontal cortex and discuss how these trajectories may help to identify sensitive periods during which environmental exposures, such as those associated with increased risk for schizophrenia, might lead to the types of abnormalities in prefrontal cortical function present in schizophrenia.
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Affiliation(s)
- Gil D. Hoftman
- Medical Scientist Training Program, University of Pittsburgh, Pittsburgh, PA,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
| | - David A. Lewis
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA,Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA,To whom correspondence should be addressed; 3811 O'Hara Street, Biomedical Science Tower, W-1654, Pittsburgh, PA 15213, US; tel: 412-383-8548, fax: 412-624-9910, e-mail:
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195
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Arnsten AFT. Prefrontal cortical network connections: key site of vulnerability in stress and schizophrenia. Int J Dev Neurosci 2011; 29:215-23. [PMID: 21345366 PMCID: PMC3115784 DOI: 10.1016/j.ijdevneu.2011.02.006] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 02/02/2011] [Accepted: 02/03/2011] [Indexed: 01/01/2023] Open
Abstract
The symptoms of schizophrenia involve profound dysfunction of the prefrontal cortex (PFC). PFC networks create our "mental sketch pad", and PFC dysfunction contributes to symptoms such as cognitive deficits, thought disorder, delusions and hallucinations. Neuropathological studies of schizophrenia have shown marked loss of dendritic spines in deep layer III, the sublayer where PFC microcircuits reside. The microcircuits consist of recurrent excitatory pyramidal cell networks that interconnect on spines, and excite each other via NMDA receptor signaling. The pyramidal cell persistent firing is sculpted by lateral inhibition from GABAergic basket and chandelier cells, thus creating tuned, persistent firing needed for accurate representational knowledge (i.e., working memory). The strength of pyramidal cell network connections is markedly and flexibly altered by intracellular signaling pathways in dendritic spines, a process called dynamic network connectivity (DNC). DNC proteins such as HCN channels are concentrated on dendritic spines in deep layer III. Under optimal conditions, network inputs to pyramidal cells are strengthened by noradrenergic alpha-2A inhibition of cAMP-HCN channel signaling, and sculpted by dopamine D1-cAMP-HCN channel weakening of inappropriate inputs. However, with stress exposure, high levels of cAMP-HCN channel signaling produces a collapse in network firing. With chronic stress exposure, spines reduce in size and are lost, and this process involves increased PKC signaling. Importantly, molecules that normally strengthen PFC networks connections and/or reverse the stress response, are often genetically altered in schizophrenia. As exposure to stress is a key factor in the precipitation of schizophrenic symptoms, these dysregulated signaling pathways in deep layer III may interact with already vulnerable circuitry to cause spine loss and the descent into illness.
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Affiliation(s)
- Amy F T Arnsten
- Department of Neurobiology, Yale Medical School, 333 Cedar St., New Haven, CT 06510, USA.
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196
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Gamma synchrony: towards a translational biomarker for the treatment-resistant symptoms of schizophrenia. Neuropharmacology 2011; 62:1504-18. [PMID: 21349276 DOI: 10.1016/j.neuropharm.2011.02.007] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/01/2011] [Accepted: 02/07/2011] [Indexed: 12/22/2022]
Abstract
The lack of efficacy for antipsychotics with respect to negative symptoms and cognitive deficits is a significant obstacle for the treatment of schizophrenia. Developing new drugs to target these symptoms requires appropriate neural biomarkers that can be investigated in model organisms, be used to track treatment response, and provide insight into pathophysiological disease mechanisms. A growing body of evidence indicates that neural oscillations in the gamma frequency range (30-80 Hz) are disturbed in schizophrenia. Gamma synchrony has been shown to mediate a host of sensory and cognitive functions, including perceptual encoding, selective attention, salience, and working memory - neurocognitive processes that are dysfunctional in schizophrenia and largely refractory to treatment. This review summarizes the current state of clinical literature with respect to gamma-band responses (GBRs) in schizophrenia, focusing on resting and auditory paradigms. Next, preclinical studies of schizophrenia that have investigated gamma-band activity are reviewed to gain insight into neural mechanisms associated with these deficits. We conclude that abnormalities in gamma synchrony are ubiquitous in schizophrenia and likely reflect an elevation in baseline cortical gamma synchrony ('noise') coupled with reduced stimulus-evoked GBRs ('signal'). Such a model likely reflects hippocampal and cortical dysfunction, as well as reduced glutamatergic signaling with downstream GABAergic deficits, but is probably less influenced by dopaminergic abnormalities implicated in schizophrenia. Finally, we propose that analogous signal-to-noise deficits in the flow of cortical information in preclinical models are useful targets for the development of new drugs that target the treatment-resistant symptoms of schizophrenia.
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197
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Möhler H, Boison D, Singer P, Feldon J, Pauly-Evers M, Yee BK. Glycine transporter 1 as a potential therapeutic target for schizophrenia-related symptoms: evidence from genetically modified mouse models and pharmacological inhibition. Biochem Pharmacol 2011; 81:1065-77. [PMID: 21333635 DOI: 10.1016/j.bcp.2011.02.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 02/09/2011] [Accepted: 02/09/2011] [Indexed: 12/18/2022]
Abstract
Schizophrenia is characterized by positive symptoms such as hallucinations, negative symptoms such as blunted affect, and symptoms of cognitive deficiency such as deficits in working memory and selective attention. N-methyl-d-aspartate receptor (NMDAR) hypofunction has been implicated in all three pathophysiological aspects of the disease. Due to the severe side effects of direct NMDAR agonists, targeting the modulatory co-agonist glycine-B site of the NMDAR is considered to be a promising strategy to ameliorate NMDAR hypofunction. To assess the antipsychotic and pro-cognitive potential of this approach, we examine the strategies designed to enhance glycine-B site occupancy through glycine transporter 1 (GlyT1) blockade. Among the existing transgenic mouse models with GlyT1 deficits, the one specifically targeting forebrain neuronal GlyT1 has yielded the most promising data on cognitive enhancement. Parallel advances in the pharmacology of GlyT1 inhibition point not only to an enhancement of attention, learning and memory but also include suggestions of mood enhancing effects that might be valuable for treating negative symptoms. Thus, interventions at GlyT1 are highly effective in modifying multiple brain functions, and dissection of their respective mechanisms is expected to further maximize their therapeutic potential for human mental diseases.
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Affiliation(s)
- Hanns Möhler
- Institute of Pharmacology, University and ETH Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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198
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Adenosine hypothesis of schizophrenia--opportunities for pharmacotherapy. Neuropharmacology 2011; 62:1527-43. [PMID: 21315743 DOI: 10.1016/j.neuropharm.2011.01.048] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/21/2011] [Accepted: 01/28/2011] [Indexed: 12/19/2022]
Abstract
Pharmacotherapy of schizophrenia based on the dopamine hypothesis remains unsatisfactory for the negative and cognitive symptoms of the disease. Enhancing N-methyl-D-aspartate receptors (NMDAR) function is expected to alleviate such persistent symptoms, but successful development of novel clinically effective compounds remains challenging. Adenosine is a homeostatic bioenergetic network modulator that is able to affect complex networks synergistically at different levels (receptor-dependent pathways, biochemistry, bioenergetics, and epigenetics). By affecting brain dopamine and glutamate activities, it represents a promising candidate for reversing the functional imbalance in these neurotransmitter systems believed to underlie the genesis of schizophrenia symptoms, as well as restoring homeostasis of bioenergetics. Suggestion of an adenosine hypothesis of schizophrenia further posits that adenosinergic dysfunction might contribute to the emergence of multiple neurotransmitter dysfunctions characteristic of schizophrenia via diverse mechanisms. Given the importance of adenosine in early brain development and regulation of brain immune response, it also bears direct relevance to the aetiology of schizophrenia. Here, we provide an overview of the rationale and evidence in support of the therapeutic potential of multiple adenosinergic targets, including the high-affinity adenosine receptors (A(1)R and A(2A)R), and the regulatory enzyme adenosine kinase (ADK). Key preliminary clinical data and preclinical findings are reviewed.
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199
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Nakazawa K, Zsiros V, Jiang Z, Nakao K, Kolata S, Zhang S, Belforte JE. GABAergic interneuron origin of schizophrenia pathophysiology. Neuropharmacology 2011; 62:1574-83. [PMID: 21277876 DOI: 10.1016/j.neuropharm.2011.01.022] [Citation(s) in RCA: 349] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/11/2011] [Accepted: 01/13/2011] [Indexed: 12/16/2022]
Abstract
Hypofunction of N-methyl-d-aspartic acid-type glutamate receptors (NMDAR) induced by the systemic administration of NMDAR antagonists is well known to cause schizophrenia-like symptoms in otherwise healthy subjects. However, the brain areas or cell-types responsible for the emergence of these symptoms following NMDAR hypofunction remain largely unknown. One possibility, the so-called "GABAergic origin hypothesis," is that NMDAR hypofunction at GABAergic interneurons, in particular, is sufficient for schizophrenia-like effects. In one attempt to address this issue, transgenic mice were generated in which NMDARs were selectively deleted from cortical and hippocampal GABAergic interneurons, a majority of which were parvalbumin (PV)-positive. This manipulation triggered a constellation of phenotypes--from molecular and physiological to behavioral--resembling characteristics of human schizophrenia. Based on these results, and in conjunction with previous literature, we argue that during development, NMDAR hypofunction at cortical, PV-positive, fast-spiking interneurons produces schizophrenia-like effects. This review summarizes the data demonstrating that in schizophrenia, GABAergic (particularly PV-positive) interneurons are disrupted. PV-positive interneurons, many of which display a fast-spiking firing pattern, are critical not only for tight temporal control of cortical inhibition but also for the generation of synchronous membrane-potential gamma-band oscillations. We therefore suggest that in schizophrenia the specific ability of fast-spiking interneurons to control and synchronize disparate cortical circuits is disrupted and that this disruption may underlie many of the schizophrenia symptoms. We further argue that the high vulnerability of corticolimbic fast-spiking interneurons to genetic predispositions and to early environmental insults--including excitotoxicity and oxidative stress--might help to explain their significant contribution to the development of schizophrenia.
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Affiliation(s)
- Kazu Nakazawa
- Unit on Genetics of Cognition and Behavior, National Institute of Mental Health, Department of Health and Human Services, Bethesda, MD 20892, USA.
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200
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Meyer U, Feldon J. To poly(I:C) or not to poly(I:C): advancing preclinical schizophrenia research through the use of prenatal immune activation models. Neuropharmacology 2011; 62:1308-21. [PMID: 21238465 DOI: 10.1016/j.neuropharm.2011.01.009] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/05/2011] [Accepted: 01/07/2011] [Indexed: 10/18/2022]
Abstract
The neurodevelopmental hypothesis of schizophrenia has been highly influential in shaping our current thinking about modeling the disease in animals. Based on the findings provided by human epidemiological studies, a great deal of recent interest has been centered upon the establishment of neurodevelopmental rodent models in which the basic experimental manipulation takes the form of prenatal exposure to infection and/or immune activation. One such model is based on prenatal treatment with the inflammatory agent poly(I:C) (=polyriboinosinic-polyribocytidilic acid), a synthetic analog of double-stranded RNA. Since its initial establishment and application to basic schizophrenia research, the poly(I:C) model has made a great impact on researchers concentrating on the neurodevelopmental and neuroimmunological basis of complex human brain disorders such as schizophrenia, and as a consequence, the model now enjoys wide recognition in the international scientific community. The present article emphasizes that the poly(I:C) model has gained such impact because it successfully accounts for several aspects of schizophrenia epidemiology, pathophysiology, symptomatology, and treatment. The numerous features of this experimental system make the poly(I:C) model a very powerful neurodevelopmental animal model of schizophrenia-relevant brain disease which is expected to be capable of critically advancing our knowledge of how the brain, following an (immune-associated) triggering event in early life, can develop into a "schizophrenia-like brain" over time. Furthermore, the poly(I:C) model seems highly suitable for the exploration of novel pharmacological and neuro-immunomodulatory strategies for both symptomatic and preventive treatments against psychotic disease, as well as for the identification of neurobiological mechanisms underlying gene-environment and environment-environment interactions presumably involved in the etiology of schizophrenia and related disorders.
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Affiliation(s)
- Urs Meyer
- Laboratory of Behavioral Neurobiology, Swiss Federal Institute of Technology (ETH) Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
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